The subject matter disclosed herein relates to a high temperature thermal expansion compensator.
High-temperature thermoelectric materials are generally brittle, they have a relatively high Young's Modulus and relatively low allowable strain. They also exhibit low ultimate tensile strength. Several classes of thermoelectric materials exist with different values for their coefficients of thermal expansion. When thermoelectric materials from two different classes are combined to form a new thermoelectric couple, then, the difference in their coefficient of thermal expansions requires that a compensation device be included within the structural frame of the couple to prevent buildup of high stress levels in the thermoelectric couple legs and their potential to fracture.
The required properties for such a compensator include a very low effective Young's Modulus, they should allow for high elastic strain, they should be compatible with the operating environment and have the capability to demonstrate metallurgical bonding of the compensator into the thermoelectric couple's electrodes. There are no known materials, or combination of materials in the form of gradated structures, which can satisfy all four criteria for the compensator simultaneously.